August 2012. New Caledonia asked what are these holes in sweetpotato roots? They are circular and not very deep, and internally the flesh is not damaged. However, the damage affects the commercial value of the roots.
The damage was thought to be due to wireworms, and it was suggested to have a look in the soil around the roots to find the adults (click beetles) or the larvae. They are generalist feeders and you can often find the adults on the soil surface and sometimes contaminating plants, while the larval stages stays in the soil.
Members of the Australian Sweetpotato Association wrote: “The larval stage of either a scarab beetle, possible click beetle or a weevil such a white fringed weevil. Since the injury looks superficial (only skin deep?) it suggests the larvae have matured in the soil”.
There seems to be both old, healed feeding injury, and more recent fresh feeding; this might suggest it is one of the more robust soil larvae pests due to size of injury and it’s ability to withstand higher soil temperature and moisture near the surface of the soil (depending on how the season was and how the grower manages his crop agronomically of course).
Other suggestions were sweetpotato weevil and millipedes, but neither of these were thought likely.